Method and apparatus for interactive annotation and measurement of time series data with automatic marker sequencing

ABSTRACT

A system displays time-series data, such as electrocardiographic data. The data may be displayed as a trace with markers identifying data features. The markers may be automatically sequenced by the system.

FIELD OF THE INVENTION

[0001] The invention relates to display systems and, more particularly,to interactive displays for the presentation, annotation, and analysisof the features of electrocardiogram waveforms and other time seriesdata.

BACKGROUND OF THE INVENTION

[0002] A number of interactive display devices have been developed toprovide immediate visual feedback to the user of a computer, or otherelectronic or electromechanical equipment, and to thereby allow the userto precisely control operations related to the display. The movement ofa cursor on a display, for example, permits me to insert words withintext as I type this document. Similarly, by activating a slide bar atone side of the display, I can scroll through the document much morerapidly. Pull-down and pop-up menus permit me to activate otherfunctions, such as saving or printing a document, checking the spellingof a document, etc. The display is interactive in the sense that signalsfrom an input device, such as a keyboard, a mouse, touch-pad,touch-screen, or voice input system, is reflected in the modification ofthe display and in an underlying modification of data related to thedisplay. That is, for example, not only is the cursor moved on thescreen in response to input from the mouse, the underlying document,stored in electronic form within the computer I'm using, also reflectsthe cursor movement.

[0003] The real-time display provided by endoscopic instruments duringsurgery allows a surgeon to precisely control the position, direction,and speed of surgical tools in the process of delicate brain surgerythat would otherwise be impossible. Although the tool might bepositioned physically by powerful magnets, for example, control of themagnets and ultimately of the surgical tools, is in the hands of asurgeon. The surgeon may rely upon a display to provide him withimmediate visual feedback via a live video feed while he employs ajoystick or other input device to control the surgical tool. The surgeonmay be operating by “dead reckoning” in that the only feedback he may bereceiving is from the video feed and from some sort of an indicatorwhich reveals the position of the tool within the patient, withoutrevealing anything about the tool itself, that is, any changes in thecross-section of the tool, for example.

[0004] Interactive display devices are also used in the analysis ofcomplex data sets. Insight may be gained by viewing the data in a uniquemanner that permits the visual correlation of data. Just as Linneaus'binomial organization of biological specimens into species and genusprovided an organizational framework for understanding the vastdiversity of the biosphere, an opportune display of data or of theresults of operations performed on the data, may allow a user to gaininsights that might otherwise be overlooked.

[0005] Although current interactive displays provide adequate feedbackfor many applications, there is a need for an interactive display whichprovides visual feedback to a user for operations that are more complexthan simply positioning a cursor within a field of text. In particular,the display and on-screen measurement of time series data, such aselectrocardiogram data, would be highly desirable.

SUMMARY

[0006] An interactive display system in accordance with the principlesof the invention includes an input device, a controller, and a display.The controller is configured to display time-series data, such aselectrocardiogram data, in graphical form, on the display. Thecontroller is also configured to position one or more markers on thedisplay, as dictated by user input received through an input device, andto correlate the underlying data to the point(s) indicated by the markerposition.

[0007] The controller may be responsive to signals from the input deviceby modifying the size, shape, position, or other aspects of the marker.Such modifications to the marker are provided as a visual feedbackmechanism for a user. In addition to the marker modification, thecontroller may operate on data, or provide an indication to anothercontroller that the data should be operated upon, in a predeterminedmanner corresponding to the manipulation of the marker. For example, atime interval may be marked off by the manipulation of one or moremarkers, and the controller may respond, not only by positioning themarkers according to user input, but also by computing the time and/orother values (e.g., average signal level over the interval).Additionally, modifications to the position of the marker may bereflected by modifications to information displayed, with, for example,the coordinates of one or more markers displayed and updated “on thefly” as a marker is repositioned on the display. The coordinates mayrepresent a multi-dimensional space in which dimensions are devoted tosignal level, time, event number, or other variables, for example.Markers may be combined with other interactive display devices andtechniques such as pulldown or popup menus, or sliders, for example.

[0008] In an illustrative embodiment, the interactive display presentselectrocardiogram data in a manner that emulates the standard paperrecording format. For example, data from a standard ECG recording may bedisplayed as traces overlaid on a millimeter grid reference background.By displaying ECG data in much the same format as that of a conventionalECG paper printout, the system capitalizes on the pattern recognitionskills developed by cardiologists through years of training andexperience. Moreover, the interactive display system maintains theaspect ratio, thereby preserving the pattern-recognition advantages,during electronic magnification (zoom) operations. By preserving theaspect ratio in this manner, doubling, for example, both the horizontaland vertical scales for both the ECG waveform and the reference grid fora 2× magnified view of an ECG, a cardiologist may make precise,highly-refined ECG measurements, even while viewing an undistortedrepresentation of the ECG.

[0009] A user may select one or more features of interest bymanipulating one or more markers. Each marker may be a conventionalmarker, such as a cursor such as is used in word-processingapplications, for example. Alternately, a marker may be a vertical linethat intersects the waveform and has an associated alphanumericcharacter, such as a “P” (corresponding to atrial depolarization) toidentify the meaning of the marked point. The marker may also be conic,such as a graphic corresponding to a frontal plane QRS axis, forexample. Intervals, such as PR, QRS, QT, and RR intervals, may bemeasured on-screen using one or more markers. That is, for example, auser may employ a single marker to indicate a point for whichmeasurements, such as voltage and time, are desired. The user may use asingle marker to set the beginning of an interval for which measurementsare desired, then place a marker at the end of the desired interval, ora plurality of markers may be employed to denote data values or dataintervals of interest.

[0010] Multiple markers may also be employed, with one assigned to markthe beginning of an interval and one assigned to mark the end of aninterval of interest, for example. The interactive display system alsoprovides for “automatic” marking. For example, in one mode of operationa user may mark the QRS onset feature on a trace of interest in responseto which the system completes the markings for the P (P onset), J (QRSend), and T (T wave end) points and computes the intervals associatedwith this beat. Measurements may be displayed in close proximity to themeasurement marks, overlaid on the strip chart background, and/or may bedisplayed in one or more separate “reporting areas on the display. Thedisplayed measurements may be updated continuously, so that, as a markeris moved across the strip chart background, the measurement displaycontinuously changes to reflect the updated position of the marker.Alternatively, the displayed measurements may be updated uponfinalization of a marker position. The finalization may be effectedthrough use of an “enter” keystroke, for example.

[0011] The time-series data may be obtained directly from anelectrocardiogram machine that provides digital output. If theelectrocardiogram machine provides only analog output, the analogsignal(s) may be converted to digital form for processing by aninteractive display in accordance with the principles of the presentinvention. Whether the analog ECG signals are converted to digital formby the ECG machine or in post-processing, a user may process thecorresponding digital data on the interactive display directly from theECG machine or from stored ECG data. Additionally, one or more users mayuse an interactive display in accordance with the principles of thepresent invention to process ECG data that is obtained at one or morepatient sites and transmitted, via a telecommunications network, forexample, to an ECG analysis center. Digitized ECG data may betransmitted to an analysis center and stored for future processing orplaced in a queue for immediate processing. Alarms of varying degrees ofurgency may be activated by an interactive display in accordance withthe principles of the present invention in response to ECG dataanalyses.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and further features, aspects, and advantages of theinvention will be apparent to those skilled in the art from thefollowing detailed description, taken together with the accompanyingdrawings in which:

[0013]FIG. 1 is a conceptual block diagram of a system that may employan interactive display in accordance with the principles of theinvention;

[0014]FIG. 2 is a conceptual block diagram of a system that may employ aremote data collection process through a telecommunications network inaccordance with the principles of the invention;

[0015]FIG. 3 is an illustrative display screen that contains a standard12 lead resting ECG in a standard configuration of 10 seconds by 12leads. This screen is also used to illustrate some of the interactivefeatures and display areas of a display in accordance with theprinciples of the present invention;

[0016]FIG. 4 is an illustrative display screen that contains anotherformat of a standard 12 lead resting ECG—2 groups of 6 leads with 5seconds of data per lead group. This screen is also used to illustratesome of the interactive features and display areas in accordance withthe principles of the present invention;

[0017]FIG. 5 is similar to FIG. 3 with the addition of the displayfeature to include the presentation of a median beat or other deriveddata. This figure also illustrates the placement of annotation markersto identify waveform features in accordance with the principles of thepresent invention;

[0018]FIG. 6 is similar to FIG. 4 with the addition of the displayfeature to include the presentation of a comparison ECG waveform inaccordance with the principles of the present invention;

[0019]FIG. 7 is an illustrative display screen that shows a 2× expandedwaveform to illustrate the equal expansion of the vertical andhorizontal aspects of the waveform display in accordance with theprinciples of the present invention;

[0020]FIG. 8 is an illustrative display screen that shows examples ofthe waveform measurement display for the current marker, the currentlead, and the overall summary measurements in accordance with theprinciples of the present invention. This figure also shows a 4×expanded waveform display in accordance with the principles of thepresent invention;

[0021]FIG. 9 is an illustrative display screen that shows a 8× expandedwaveform to illustrate the equal expansion of the vertical andhorizontal aspects of the waveform display in accordance with theprinciples of the present invention. This figure also illustrates theability to display a single lead for detailed analysis in accordancewith the principles of the present invention;

[0022]FIG. 9a is an illustrative display screen that shows an example ofthe waveform in FIG. 9 displayed at ½ scale (vertical scale is reducedto ½ while the horizontal scale is maintained) in accordance with theprinciples of the present invention;

[0023]FIG. 10 is an illustrative display screen that shows an exampletext report display and editing function with related data entry andoption selection features in accordance with the principles of thepresent invention.

[0024]FIG. 11 is an illustrative display screen that shows an examplethat extends the editing features to include the menu selection of codedand textual statements that will become part of the ECG report inaccordance with the principles of the present invention;

[0025]FIG. 12 is a conceptual block diagram of a system that may employmore than one interactive display in accordance with the principles ofthe invention. This diagram shows the potential interactions betweensystem elements and interactive displays in accordance with theprinciples of the present invention.

[0026]FIG. 13 is a conceptual detailed block diagram of a system thatmay employ additional analysis functions in support of the interactivedisplay in accordance with the principles of the invention. This diagramalso illustrates how the system may employ additional queuing and datacontrol functions in support of the interactive display in accordancewith the principles of the invention.

[0027]FIG. 14 is an illustrative display screen that shows an example ofhow derived data such as the time derivative of the time series waveformdata may be presented with the original data to assist in the analysisof the data. This figure also illustrates an alternative method for thedisplay of comparison time series waveform data may be displayed inaccordance with the principles of the current invention;

[0028]FIG. 15 is an illustrative display screen that shows an example ofthe menu that may be used to indicate acceptance of the edited reportand enter instructions for subsequent processing in accordance with theprinciples of the present invention;.

DETAILED DESCRIPTION

[0029]FIG. 1 illustrates the system architecture for a computer system100 on which the invention may be implemented. The exemplary computersystem of FIG. 1 is for descriptive purposes only. Although thedescription may refer to terms commonly used in describing particularcomputer systems, the description and concepts equally apply to othersystems, including systems having architectures dissimilar to FIG. 1.

[0030] Computer system 100 includes a central processing unit (CPU) 105,which may be implemented with a conventional microprocessor, a randomaccess memory (RAM) 110 for temporary storage of information, and a readonly memory (ROM) 115 for permanent storage of information. A memorycontroller 120 is provided for controlling RAM 110.

[0031] A bus 130 interconnects the components of computer system 100. Abus controller 125 is provided for controlling bus 130. An interruptcontroller 135 is used for receiving and processing various interruptsignals from the system components.

[0032] Mass storage may be provided by diskette 142, CD ROM 147, or harddrive 152. Data and software may be exchanged with computer system 100via removable media such as diskette 142 and CD ROM 147. Diskette 142 isinsertable into diskette drive 141 which is, in turn, connected to bus130 by a controller 140. Similarly, CD ROM 147 is insertable into CD ROMdrive 146 which is, in turn, connected to bus 130 by controller 145.Hard disc 152 is part of a fixed disc drive 151 which is connected tobus 130 by controller 150.

[0033] User input to computer system 100 may be provided by a number ofdevices. For example, a keyboard 156 and mouse 157 are connected to bus130 by controller 155. An audio transducer 196, which may act as both amicrophone and a speaker, is connected to bus 130 by audio controller197, as illustrated. It will be obvious to those reasonably skilled inthe art that other input devices, such as a pen and/or tabloid may beconnected to bus 130 and an appropriate controller and software, asrequired. DMA controller 160 is provided for performing direct memoryaccess to RAM 110. A visual display is generated by video controller 165which controls video display 170. Computer system 100 also includes acommunications adaptor 190 which allows the system to be interconnectedto a local area network (LAN) or a wide area network (WAN),schematically illustrated by bus 191 and network 195. An input interface199 operates in conjunction with an input device 193 to permit a user tosend information, whether command and control, data, or other types ofinformation, to the system 100. The input device and interface may beany of a number of common interface devices, such as a joystick, atouch-pad, a touch-screen, a speech-recognition device, or other knowninput device.

[0034] Operation of computer system 100 is generally controlled andcoordinated by operating system software. The operating system controlsallocation of system resources and performs tasks such as processingscheduling, memory management, networking, and I/O services, amongthings. In particular, an operating system resident in system memory andrunning on CPU 105 coordinates the operation of the other elements ofcomputer system 100. The present invention may be implemented with anynumber of commercially available operating systems including Windows,OS/2, UNIX and DOS, etc. One or more applications may also run on theCPU 105. If the operating system is a true multitasking operatingsystem, multiple applications may execute simultaneously.

[0035] As will be understood by those skilled in the art,Object-Oriented Programming (OOP) techniques involve the definition,creation, use and destruction of “objects”. These objects are softwareentities comprising data elements, or attributes, and methods, orfunctions, which manipulate the data elements. The attributes andrelated methods are treated by the software as an entity and can becreated, used and deleted as if they were a single item. Together, theattributes and methods enable objects to model virtually any real-worldentity in terms of its characteristics, which can be represented by thedata elements, and its behavior, which can be represented by its datamanipulation functions. In this way, objects can model concrete thingslike people and computers, and they can also model abstract conceptslike numbers or geometrical designs.

[0036] Objects are defined by creating “classes” which are not objectsthemselves, but which act as templates that instruct the compiler how toconstruct the actual object. A class may, for example, specify thenumber and type of data variables and the steps involved in the methodswhich manipulate the data. When an object-oriented program is compiled,the class code is compiled into the program, but no objects exist.Therefore, none of the variables or data structures in the compiledprogram exist or have any memory allotted to them. An object is actuallycreated by the program at runtime by means of a special function calleda constructor which uses the corresponding class definition andadditional information, such as arguments provided during objectcreation, to construct the object. Likewise, objects are destroyed by aspecial function called a destructor. Objects may be used by using theirdata and invoking their functions. When an object is created at runtimememory is allotted and data structures are created.

[0037] The principle benefits of object-oriented programming techniquesarise out of three basic principles; encapsulation, polymorphism andinheritance. More specifically, objects can be designed to hide, orencapsulate, all, or a portion of, the internal data structure and theinternal functions. More particularly, during program design, a programdeveloper can define objects in which all or some of the attributes andall or some of the related functions are considered “private” or for useonly by the object itself. Other data or functions can be declared“public” or available for use by other programs. Access to the privatevariables by other programs can be controlled by defining publicfunctions for an object which access the object's private data. Thepublic functions form a controlled and consistent interface between theprivate data and the “outside” world. Any attempt to write program codewhich directly accesses the private variables causes the compiler togenerate an error during program compilation which error stops thecompilation process and prevents the program from being run.

[0038] Polymorphism is a concept which allows objects and functionswhich have the same overall format, but which work with different data,to function differently in order to produce consistent results. Forexample, an addition function may be defined as variable A plus variableB (A+B) and this same format can be used whether the A and B arenumbers, characters or dollars and cents. However, the actual programcode which performs the addition may differ widely depending on the typeof variables that comprise A and B. Polymorphism allows three separatefunction definitions to be written, one for each type of variable(numbers, characters and dollars). After the functions have beendefined, a program can later refer to the addition function by itscommon format (A+B) and, at runtime, the program will determine which ofthe three functions is actually called by examining the variable types.Polymorphism allows similar functions which produce analogous results tobe “grouped” in the program source code to produce a more logical andclear program flow.

[0039] The third principle which underlies object-oriented programmingis inheritance, which allows program developers to easily reusepre-existing programs and to avoid creating software from scratch. Theprinciple of inheritance allows a software developer to declare classes(and the objects which are later created from them) as related.Specifically, classes may be designated as subclasses of other baseclasses. A subclass “inherits” and has access to all of the publicfunctions of its base classes just as if these function appeared in thesubclass. Alternatively, a subclass can override some or all of itsinherited functions or may modify some or all of its inherited functionsmerely by defining a new function with the same form (overriding ormodification does not alter the function in the base class, but merelymodifies the use of the function in the subclass). The creation of a newsubclass which has some of the functionality (with selectivemodification) of another class allows software developers to easilycustomize existing code to meet their particular needs.

[0040]FIG. 2 illustrates conceptually the main components of aninteractive display system 200 in accordance with the present invention.A user input 202 may take the form of a known user input device anddevice interface, such as keyboard and mouse (with correspondingcontrollers), a joystick, touch pad, touch screen, voice input device,etc. in combination with controllers that may be embodied as variousinstantiations of object classes. The new interactive display engine 204may include various of the hardware components described in thediscussion related to FIG. 1. The interactive display engine 204 isconfigured to display time-series data, such as electrocardiogram data,in graphical form, on the display 206. In one aspect of an interactivedisplay in accordance with the principles of the present invention,electrocardiograms are displayed using a format that is the same as, orsubstantially similar to, standard paper recording formats. For example,data from a standard ECG recording may be displayed as traces overlaidon a millimeter grid reference background. By displaying ECG data inmuch the same format as that of a conventional ECG paper printout, thesystem capitalizes on the pattern recognition skills developed bycardiologists through years of training and experience. Moreover, theinteractive display system maintains the aspect ratio, therebypreserving the pattern-recognition advantages, during electronicmagnification (zoom) operations. By preserving the aspect ratio in thismanner, doubling, for example, both the horizontal and vertical scalesfor both the ECG waveform and the reference grid for a 2× magnified viewof an ECG, a cardiologist may make precise, highly-refined ECGmeasurements, even while viewing an undistorted representation of theECG.

[0041] The interactive display engine 204 accepts input from the userinput 202. In response to the user input, the system produces output forthe display 206 and, depending upon the user input, may record the userinput. For example, if the user selects a marker and positions it on thedisplay, the display engine 204 repositions the marker on the display.If the user also selects the marker position, by activating an “enter”key on a keyboard or “double-clicking” a mouse-button, for example thedisplay engine 204 also records the position selected by the user. Theengine 204 may also correlate, by computation for example, theunderlying data values associated with the selected screen position,then store the screen position, underlying data, and other values. Anillustrative object-oriented embodiment of the interactive displayengine includes object classes that: read data into onscreenmeasurements, provide file interfaces, provide standard interfaces todifferent ECG source types, provide standard interfaces to waveforms,provide forms that allow the selection of interpretive codes forinclusion in a code and comment segment of the report form, to pass amodified ECG to another stage in a review process, to provide displayand calculation options, to display report file text and measurementsfrom on-screen analysis and to add assessment codes and/or comments, andto select an ECG file from disk storage.

[0042] A time series medical data source 208 may take the form ofdigitized ECGs stored in computer files, data obtained locally from asubject, or ECGs obtained through a telecommunications link 210 from oneor more remote patient locations 212, for example. ECGs obtained througha telecommunications link 210 may be stored locally and processed inprioritized order, as will be described in the discussion related toFIGS. 12, for example. In an illustrative embodiment, the interactivedisplay engine 204 presents electrocardiogram data in a manner that issubstantially the same as one of the standard paper recording formats.For example, data from a 12 lead resting ECG may be displayed aswaveform traces overlaid on a millimeter grid background. By displayingECG data in much the same format as that of a conventional ECG paperprintout, the system capitalizes on the pattern recognition skillsdeveloped by cardiologists through years of training and experience.When the interactive display is used to make on-screen measurements, thetraces may be “magnified” in a number of different formats, includingone in which the aspect ratio of the displayed ECG is maintained. Thispermits the interactive display to preserve the pattern-recognitionadvantages of the display, while providing for more accurate placementof markers and a concomitant improvement in the precision of on-screenmeasurements. By preserving the aspect ratio in this manner, doubling,for example, both the horizontal and vertical ECG scales for a 2×magnified view of an ECG, a cardiologist may make precise,highly-refined ECG measurements, even while viewing an undistortedrepresentation of the ECG.

[0043] The time-series data source 208 may be obtained directly from anelectrocardiogram machine that provides digital output. If theelectrocardiogram machine provides only analog output, the analogsignal(s) may be converted to digital form for processing by aninteractive display in accordance with the principles of the presentinvention. Whether the analog ECG signals are converted to digital formby the ECG machine or in post-processing, a user may process thecorresponding digital data on the interactive display directly from theECG machine or from stored ECG data. Additionally, one or more users mayuse an interactive display in accordance with the principles of thepresent invention to process ECG data that is obtained at one or morepatient sites and transmitted, via a telecommunications network, forexample, to an ECG analysis center. Digitized ECG data may betransmitted to an analysis center and stored for future processing orplaced in a queue for immediate processing. Alarms of varying degrees ofurgency may be activated by an interactive display in accordance withthe principles of the present invention in response to ECG dataanalyses.

[0044] In various centralized embodiments of time series medical dataanalysis systems in accordance with the principles of the presentinvention, analysis and/or markup of time series medical data may beperformed at a centralized location, with data supplied to thecentralized location through a telecommunications network 210, forexample. The display engine 204 may be responsive to signals from theuser input 202 by modifying the size, shape, position, or other aspectsof the marker. Such modifications to the marker are provided as a visualfeedback mechanism for a user. In addition to the marker modification,the controller may operate on data, or provide an indication to anothercontroller that the data should be operated upon, in a predeterminedmanner corresponding to the manipulation of the marker. For example, atime interval may be marked off by the manipulation of one or moremarkers, and the engine 204 may respond, not only by positioning themarkers according to user input, but also by computing the time and/orother values (e.g., average signal level over the interval).Additionally, modifications to the position of the marker may bereflected by modifications to information displayed, with, for example,the coordinates of one or more markers displayed and updated “on thefly” as a marker is repositioned on the display. The coordinates mayrepresent a multi-dimensional space in which dimensions are devoted tosignal level, time, event number, or other variables, for example.Markers may be combined with other interactive display devices andtechniques such as pull-down or popup menus, buttons, or sliders, forexample.

[0045] In an illustrative embodiment, the interactive display presentselectrocardiogram data in a manner that emulates conventionalstrip-chart recorders. That is, the ECG data are displayed as waveformtraces overlaid on a millimeter grid background. In a display mode thatmay be used as a default, each grid division, or cell, represents 40milliseconds along the abscissa and 0.1 millivolt along the ordinate.Multi-grid divisions may be “set off” by employing heavier grid linesevery fifth division, for example, to form 200 millisecond by 0.5millivolt “super-cells.” A 1280×1024 pixel display that employs an1220×690 pixel area for the display of waveforms may employ one pixelfor every eight milliseconds (five pixels per millimeter) in displayinga standard 1 mm×1 mm, 40 ms×0.1 mV grid. Various “zoom” schemes may beemployed to increase or decrease the resolution of the display byincreasing or decreasing the number of pixels dedicated to eachmillisecond and/or millivolt. A user may select one or more features ofinterest by manipulating one or more markers. Each marker may be aconventional marker, such as a cursor such as is used in word-processingapplications, for example. Alternately, a marker may be a vertical linethat intersects the waveform and has an associated alphanumericcharacter, such as a “P” (corresponding to the beginning of atrialdepolarization) to identify the meaning of the marked point. The markermay also be iconic, such as a graphic corresponding to a frontal planeQRS axis, for example. Intervals, such as PR, QRS, QT, and RR intervals,may be measured on-screen using one or more markers. That is, forexample, a user may employ a single marker to indicate a point for whichmeasurements, such as voltage and time, are desired. The user may use asingle marker to set the beginning of an interval for which measurementsare desired, then place another marker at the end of the desiredinterval, or a plurality of markers may be employed to denote datavalues or data intervals of interest.

[0046] Multiple markers may also be employed, with one assigned to markthe beginning of an interval and one assigned to mark the end of aninterval of interest, for example. The interactive display system alsoprovides for “automatic” marking. For example, in one mode of operationa user may mark a “Q” feature on a trace of interest in response towhich the system completes the markings for the P, J, and T points, orfeatures, and computes the QRS interval and other measurementsassociated with the marked points and associated medically significantartifact. Measurements may be displayed in close proximity to themeasurement marks, overlaid on the strip chart background, and/or may bedisplayed in one or more separate “reporting areas” on the display. Thedisplayed measurements may be updated continuously, so that, as a markeris moved across the strip chart background, the measurement displaycontinuously changes to reflect the updated position of the marker.Alternatively, the displayed measurements may be updated uponfinalization of a marker position. The finalization may be effectedthrough use of an “enter” keystroke, for example.

[0047] The time-series data may be obtained directly from anelectrocardiogram machine that provides digital output. If theelectrocardiogram machine provides only analog output, the analogsignal(s) may be converted to digital form for processing by aninteractive display in accordance with the principles of the presentinvention. Whether the analog ECG signals are converted to digital formby the ECG machine or in post-processing, a user may process thecorresponding digital data on the interactive display directly from theECG machine or from stored ECG data.

[0048] The screen shot of FIG. 3 is illustrative of a display output inaccordance with the principles of the present invention. A user mayselect one or more features of interest by manipulating one or moremarkers. Each marker may be a conventional marker, such as a cursor suchas is used in word-processing applications, for example. Alternately, amarker may be a vertical line that intersects the waveform and has anassociated alphanumeric character, such as a “P” (corresponding to thebeginning of atrial depolarization) to identify the meaning of themarked point. The marker may also be iconic, such as a graphiccorresponding to a frontal plane QRS axis, for example. Intervals, suchas PR, QRS, QT, and RR intervals, may be measured on-screen using one ormore markers. That is, for example, a user may employ a single marker toindicate a point for which measurements, such as voltage and time, aredesired. The user may use a single marker to set the beginning of aninterval for which measurements are desired, then place another markerat the end of the desired interval, or a plurality of markers may beemployed to denote data values or data intervals of interest.

[0049] Multiple markers may also be employed, with one assigned to markthe beginning of an interval and one assigned to mark the end of aninterval of interest, for example. The interactive display system alsoprovides for “automatic” marking. For example, in one mode of operationa user may mark a “Q” feature on a trace of interest in response towhich the system completes the markings for the P, J, and T markers andcomputes the measurements associated with the beat, that is, the PRinterval, the QRS duration, and the QT interval. Once a typical set ofmarkers have been placed, the system may sequence through all beats andplace markers for these points. The system may operate through otherautomatic sequences related to the selection of particular measurementpoints, such as the location and measurement of a point to measure STelevation or depression. An operator may define a set of marks as anauto-sequence to allow the system to replicate measurements based on thesample markers placed during the definition. Sequences of marks may beautomatically placed either through operator initiation of the operationor based on specific requirements for sets of ECGs where annotationmarks will be automatically placed for operator verification. Suchfeatures as automatically marking the peaks of waveform features as wellas the onset and offset of detailed features are supported b theprinciples of the present invention.

[0050] Measurements may be displayed in close proximity to themeasurement marks, overlaid on the strip chart background, and/or may bedisplayed in one or more separate “reporting areas on the display. Forexample, in the illustrative screen shot of FIG. 3, an informationbutton 300 may be used to alert an operator in some way. For example, inthis illustrative screen shot, the button 300 features a white button ona red background to indicate an emergency read condition. By activatingthe button (e.g., by “clicking on” the button) the operator may obtainmore information related to the ECG data set, related, for example, tothe nature of the emergency. Various indicators, such as flashing, colorchanges, the use of specific colors, different levels of transparency,and other display techniques may be used to alert an operator to variousconditions related to the button 300 or other features displayed on aninteractive display in accordance with the principles of the presentinvention. Other conditions may be signaled by operation of the button300. For example, a blue background with a white “i” substituted for theX, may be used to indicate that further information is available to anoperator and that it may be obtained by clicking on the button 300.Protocol information may be obtained through activation of the protocolbutton 302. In this illustrative example, the start time, resolution ofthe display, and the number of leads for which data are displayed arerespectively displayed in windows 304, 306, and 308. The windows mayinclude up/down arrows, such as arrows 310 to allow an operator toselect different resolutions or number of leads displayed, for example.

[0051] The display may also include an indication of the number of jobswaiting to be serviced, as indicated by the window 312. The start timeis the initial offset of the starting point on the screen with referenceto the beginning point of data collection. The “resolution” featureincluded in this illustrative display indicates the relationship of thewaveform display to the physical display. The 8 ms resolution means 8ms/pixel. This is the standard starting display resolution in thisillustrative embodiment. By decreasing the resolution, the magnificationof the displayed waveform is increased. Decreasing the resolution to 4ms would double the size of the displayed waveform. The display of thebackground millimeter grid is also based on the resolution setting. Ifthe number of pixels on the display between 1 millimeter grid markswould cause the grid to make the waveform difficult to read, thebackground grid is reduced to 5 millimeter increments. An option is alsoprovided to temporarily eliminate the background grid if desired. Theinvention is not limited to the concept of using the smallest viewablefeature of the display as the maximum resolution. The “Leads” optionpermits an operator to increase or decrease the number of leads that aredisplayed vertically on the screen. The system will attempt to optimizethe number of leads being displayed based on average waveforms or on theamplitude of the waveforms being presented. This option allows viewing asingle lead regardless of the magnification. The “Jobs in Queue” fieldindicates to an operator the number of separate “tracings”, e.g., ECGs,waiting to be processed by the operator on the system. In anillustrative embodiment that employs a display that utilizes 1220×690pixels of display area for the display of traces, when 8-millisecondresolution is selected, the screen is able to display 10 seconds ofdata. At 4-millisecond resolution, 5 seconds of data can be displayed.The resolution indicates the amount of time represented by each screenpixel as well as the change in Marker location when the left or rightarrow keys are pressed.

[0052] Summary measurements may be displayed in windows labeled HR, MaxP-R, Max QRS, Avg R-R, Max Q-T, and QTc, for example. The type andsequence of marker(s) to be placed on a display may be selected from theMarker Placement display menu. The options in this menu include areaslabeled PQJT Points, R-R intervals, QT Intervals, RR Intervals, QRSDuration, Q auto PJT, and Event Begin/End, for example. Data associatedwith lead containing the “active marker”, that is, the marker currentlybeing manipulated, may be displayed in the windows labeled Lead, PR,QRS, and QT. Additional windows, such as windows 314, 316 and 318 may beused to display such information as The value for all measurements basedon the current active marker (314), and the specified calculated valuesfor all measurements in the currently active lead. Items 316 and 318 aredisplay boxes that provide information about data that has been providedwith the current ECG. This information includes what previouslycalculated measurement values have been provided and when the lastreview of the ECG was done and by whom.

[0053] In an illustrative embodiment, the waveform display area includes5-mm grid lines 320 for reference. Each grid division represents 200 msin the time dimension and 0.5 mV in the voltage dimension. Theperspective of the waveform may be maintained during a “zoom” operationby magnifying the horizontal and vertical dimensions of the waveform bythe same amount. In an illustrative embodiment, the interactive displaysupports zoom operations that allow an operator to place markers withgreater precision than a full-screen twelve-lead display might otherwisepermit. The number of pixels between grid lines varies in the process ofzooming and 1 millimeter grid lines may be added during a “zoom in” inorder to provide the standard recognizable grid background for visualreference. Conversely, 1 millimeter grid lines may be deleted during a“zoom out” operation in order to avoid cluttering the display. Fivemillimeter grid lines will always be present (unless the grid linedisplay option is turned off). In an illustrative embodiment, afive-pixel threshold is employed whereby 1 mm grid lines are added tothe display when five or more pixels are required to display a distanceequal to one mm. To provide additional context, every fifth grid linemay be distinguished from the other grid lines by displaying them wider,darker, or in a different color, for example.

[0054] The display may provide for a variety of display modes, dependingon the available data and the preferences on the operator. For example,a complete 12 lead resting ECG may be displayed as 12 leads by 10seconds. It may also be displayed as 2 five second groups of 6 leadseach. Depending upon the display output device, display magnification,also referred to herein as zooming, may cause a portion of the data toexceed the display area available at any one time. The display mayprovide horizontal and/or vertical scrolling to provide access to suchdisplay information. Additionally, as the magnification of a waveform isincreased, the number of leads that can be displayed vertically withoutoverlap may be reduced. The number of leads to be displayed can eitherbe set automatically by the program to optimize the number of lead to bedisplayed or it can be manually selected to increase or decrease thenumber of leads being displayed. An operator may select a subset of the12 leads to be displayed.

[0055] The waveform's trace should be wide enough and heavy enough tomake it readily viewable at a nominal viewing distance, yet should notbe so wide and heavy as to obscure the waveform features. In anillustrative embodiment the waveform is plotted on the screen with theminimal line width that makes the waveform readily viewable with thereference grid. However, the display includes a facility that allows anoperator to adjust the waveform trace's line-width to conform to theoperator's visual requirements.

[0056] The screen shot of FIG. 4 illustrates an alternate 12 leadwaveform display screen view in accordance with the principles of thepresent invention. A vertical line 400 separates the display into twosets of six leads each. In this illustrative embodiment, the I, II, III,aVR, aVL,and aVF lead data are displayed on the left-hand side of thevertical line 400 and the V1, V2, V3, V4, V5, and V6 data are displayedon the right-hand side of the vertical line 400. The right- andleft-hand sides of the display may be sequential depending on theavailable data. That is, for example the data plotted for the V1 leadstarts at the time the data plotted for the I lead ends. This displayformat may also be used to display waveforms that are not acquiredsimultaneously. A number of markers have been placed on the screen. Inthis illustrative embodiment, the markers are vertical lines used todesignate the exact position chosen by an operator. Additionally, themarkers are multi-part, in that they are accompanied by alphanumericlabels (e.g., P,Q J, etc.), corresponding to familiar labels given toECG features.

[0057] The screen shot of FIG. 5 illustrates a split-screen display inaccordance with the principles of the present invention in which a“pane” 500, delineated by vertical line 502, may be opened to displaymedian heart beats or other derived waveform data. The median beats paneis automatically sized to display the entire beat, and so does notscroll with the rhythm waveforms. In an illustrative embodiment aninteractive display in accordance with the principles of the presentinvention provides one or more markers, such as markers 504 and 506, foruse by an operator in an on-screen measurement process involving one ormore displayed time-series waveforms. Markers 504 and 506 includealphanumerical components, indicating, in this instance, the beginningand end of an interval measurement. The markers are used to identifyon-screen measurement points and are plotted vertically and identifiedwith a label of the point or event that is being identified: the “begin”and “end” labels in this example. In an illustrative embodiment, when amarker is associated with a single lead, the marker will be limited tothe plot area occupied by that lead. When global measurement marks arebeing used, the mark will extend from the top to the bottom of the plotscreen area. The width of the markers may be selectable as an option.Initial placement of the markers may be with the use of a light pen ormouse pointer and a click. Once a marker has been placed, it becomes the“active” marker. The active marker can be moved left or right, with theresolution of one pixel at a time. When moving a marker, the timeincrement (the time represented by each pixel) will vary depending onthe selected resolution. The active marker is the one most recentlyadded, or one that has been selected. The active marker may be selectedusing a keyboard, mouse pointer, or light pen, for example. Theinteractive display may provide visual feedback to a user by, displayingthe active marker with a different color than other displayed markers,by flashing the marker, or using other display techniques. Aninteractive display in accordance with the principles of the presentinvention may also allow a user to select the color of markers and toselect the means of highlighting the active marker.

[0058] As previously noted, in accordance with the principles of thepresent invention, a twelve-lead resting ECG may be displayed in theformat normally presented on the printed page. Lead I and lead V1 willbe plotted on the same line with lead V1 starting at exactly 5 secondsafter the start of lead I. The other sets of leads will be plotted inthe same manner: II and V2, III and V3, aVR and V4, aVL and V5, and aVFand V6. The waveforms for the 60 seconds of rhythm data will bedisplayed as a single lead continuous string of waveform data. Thisformat supports making sequences of measurements across the entire setof data. The single or multi-lead waveforms for 60, 120 seconds, orlonger sets of rhythm data may be displayed, for example.

[0059] As illustrated by the screen shot of FIG. 6, comparison ECGs mayalso be displayed, using toolbar activation, file menu selection, orother user interface techniques. In an illustrative embodiment, theinteractive display permits an operator to view a comparison ECG on itsown, or, as illustrated, in a side-by-side configuration of two panes600 and 602. Report text associated with the comparison ECG may also bedisplayed under operator control, by selection from a popup menu, forexample. A plurality of comparison ECGs may be viewed, for example byselecting “next comparison” from a popup menu.

[0060] The screen shot of FIG. 7 will be used to illustrate in moredetail the placement of markers on an ECG display in accordance with theprinciples of the present invention. To place a marker on the waveform,the user may select a marker placement sequence by clicking on a markerplacement control: one of the chad-like selection mechanisms labeledPQJT Points, R-R Intervals, etc. The interactive display will start withthe first mark in the selected sequence and will provide subsequentmarkers in the proper sequence. An interactive display in accordancewith the present invention also permits an operator to annotate events,for example, by marking the beginning and end of a section of a Leadwave and attaching descriptive text to that segment. Such markers may beused to delimit and describe a section of the Lead wave without creatinga measured interval. In particular, they may be used to delimit anddescribe a section of the Lead wave, such as an ST depression, orabnormal U-wave. In an illustrative embodiment, when one of thesemarkers is selected, its descriptive text is displayed in the Status Barat the bottom of the form. In an illustrative embodiment, a sequence ofmarkers may be placed by an operator clicking and hold the left mousebutton to initiate marker placement. The interactive display may thendisplay a dotted vertical line to indicate where the marker will beplaced. The user may then move the mouse to the desired location andrelease the button to place the marker. The selected marker placementsequence (Q Auto PJT in this example, would first place the Q marker),will determine the next marker type to be placed. The label for the nextmarker is displayed in the marker placement control.

[0061] In an illustrative embodiment, after placement, the active markerposition can be adjusted using arrow keys or other user input devices.To select the active marker using an arrow key implementation, the usermay press shift and the left or right arrow key until the desired markeris highlighted, for example. To move the active marker, the user couldthen press the left or right arrow keys or use an alternate graphicinput device to indicate the marker should be moved. In thisillustrative embodiment, each time the arrow key is pressed, the markermoves by the amount indicated in the current resolution and intervalcalculations are instantly updated as a marker is moved. An interactivedisplay in accordance with the principles of the present invention mayalso provide keystroke functions to select the first and last markers asthe active marker and to shift the area of the waveform being displayed.The Home key or some other indicator may be used to center the activemarker in the viewable screen area.

[0062] The screen shot of FIG. 8 illustrates the display of activemarker data in accordance with the principles of the present invention.When matching sets of markers have been placed, intervals are calculatedfrom their positions and displayed in several boxes at the top of thewaveform. In the active marker area 802, the intervals calculated usinga method for the current lead (the lead containing the active marker)are displayed. The method used for calculation of the measured valuesmay be selected by the operator or may be set by information whichaccompanies the ECG waveform data. Directly below that (800) aredisplayed all intervals with which the active marker is associated;moving the active marker will typically impact both of these sets ofintervals. In the summary measurements area 804, the overallmeasurements are displayed; these measurements are derived from markerson all leads. The calculated values may represent, for example, eitherthe maximum lead average for which multiple intervals are marked, or theoverall maximum of each measurement, depending on the current setting ofthe summary measurement calculation option. Placing the mouse pointerover the Max P-R, Max QRS, or Max Q-T values will present a ToolTipdisplaying the Lead on which the maximum value was found. In addition,double-clicking on the Max P-R, Max QRS, or Max Q-T values willhighlight and make active the Markers representing the maximum measuredinterval of that measurement.

[0063] The screen shots of FIG. 9A and FIG. 9B illustrate the use of ahalf-scale display in accordance with the principles of the presentinvention. This optional view may be used, for example, for an ECG thatexhibits very high amplitudes, resulting in the waveforms being drawnoutside the top (902) or bottom of the display area or overlapping eachother. Note that the scale option may be exercised independently of theresolution option. When the half-scale display option is selected, thisstatus is indicated with an on-screen display 910 and with changing thecolor or other attribute of the plotted waveform, for example. Variousfilter options are accessible, in this illustrative embodiment throughinteraction with a toolbar. For example, as indicated by the tool boxeslabeled “No Filter”, “50 Hz”, and “60 Hz”, a operator may select 50 Hz,60 Hz, or no filtering of the ECG data. These filter options may be usedto assist in the analysis of noisy data without affecting the originaldata, for example.

[0064] The screen shot of FIG. 10 depicts a report form format for aninteractive display in accordance with the principles of the presentinvention. The report form includes a window 1000 that displays reportinformation. The Original Report Text area can be used to display theresults of a computer analysis of the ECG or the results of a previousoperator review, for example. The Measurement Intervals area 1014 candisplay the results of the calculations used to determine measurementvalues from the markers and that will be included in the completedreport. The Codes and Comments area, field 1008, may be used to enterinterpretive and diagnostic codes and statements and additional commentsthat are to be part of the completed report. The values in this area maybe preset by computer interpretation, prior review, or other data thatmay accompany the ECG, such as the customer ID number, for example.

[0065] In this illustrative embodiment, the interactive display includesa field 1002 of comparison statements selection options that may be usedto conveniently note trends in ECG data for a particular patient basedon a previous ECG. An operator may also employ the severity field 1004to enter information related to the overall assessment of the ECG. Asession signature field 1006 may be used to display the current date andtime and the identification of the current operator. A separate entry isrequired by the operator to be the electronic signature for the set ofentries.

[0066] In this illustrative embodiment, the display includes a Savefunction 1012 to indicate that the report editing process is complete.

[0067] In this illustrative embodiment, the display includes anInterpretive Codes function 1016 to allow the selection of interpretivecodes from a menu. An Illustrativev embodiment of the code menuselection screen is shown in FIG. 11.

[0068] As illustrated by the screen shot of FIG. 11, an interactivedisplay in accordance with the principles of the present inventionprovides a tool for an operator to select among a variety ofinterpretive codes. The types of codes are indicated by folder tabs1101, marked “overall assessment”, “comparison”, “rhythm”, A-V“conduction”, “ST segment”, etc. Each tab contains a set of code numbersand text related to the label on the tab. These code values, whenselected, will be placed in the codes and comments section, field 1008,for inclusion in the report. The complete list of selected codes isdisplayed for reference in window 1003. Provision is made for changes tomeasurements or observations that are not determined by markers, the QRSaxis for example 1104. Placing the selected codes in the Codes andComments are 1008 is accomplished by clicking on the OK button 1105, forexample.

[0069] Additionally, one or more users may use an interactive display inaccordance with the principles of the present invention to process ECGdata that is obtained at one or more patient sites and transmitted, viaa telecommunications network, for example, to an ECG analysis center.The block flow diagram of FIG. 12 depicts the flow of processing ECGdata in a central processing center in accordance with the principles ofthe present invention. Processes illustrated through the use of flowcharts or block flow diagrams may not be strictly linear processes andalternative flows may be implemented within the scope of the invention.The specific configuration of logic and/or instructions utilized toachieve a particular function, as well as other modifications to theinventive concept are contemplated within the scope of this invention.

[0070] In a time-series data processing center in accordance with theprinciples of the present invention, digitized ECG data 1200 may betransmitted to an analysis center and stored for future processing orplaced in a queue for immediate processing. Alarms of varying degrees ofurgency may be activated by an interactive display in accordance withthe principles of the present invention in response to ECG dataanalyses. In addition to ECG data, the data 1200 may include the serialnumber of a unit, such as an ECG machine, revision code of program, datacontrol card number, type of test being transmitted (12 lead, 60 second,120 second rhythm and related lead), whether this particular ECG set hasbeen transmitted before, whether battery voltage is low, for example.

[0071] In this illustrative embodiment, data is received and temporarilystored in a data control and queue manager 1202. After the file isreceived by the data control and queue manager (which could be aninstantiation of an object class, for example) 1202 the data file issent in step 1203 to data dependent analysis programs 1204. The computeranalysis program determines annotation points and creates tables ofmeasurements from these points. The analysis program may also infer,from these measurements and other data provided with the ECG, anassessment and interpretation of the ECG. The results of the analysismay be recorded in a report format similar to the intended output of theinvention. Different analysis programs may be necessary to performdifferent sets of measurements and interpretations based on the type ofECG data being provided and the reason for processing the ECG. Some orall of the results of the computer analysis may be made available to thesystem incorporating the invention to provide initial marker points oradditional information about the ECG waveform.

[0072] In step 1205 results from these programs are shipped back to thedata control and queue manager 1202. From there, the results (whichinclude measurements and waveform information) are sent to a viewingstation 1206 in step 1207. At this point, an operator, User 1, may enteror modify markers used to determine interval measurements, for example.If changes are made, the updated data may be returned to the datadependent analysis programs in step 1215 and the files are sent back tothe queue manager in step 1209.

[0073] The “marked up” waveform data, with markers and intervals, may besent to a viewing station, 1208, in step 1211. Although the viewingstation 1208 may be the same viewing station, in an illustrativeembodiment the viewing station is a separate viewing station for use bya second operator, User2. User 2 views the data and adjusts the markersas he feels necessary. User 2 may make, for example, changes andadditions that he feels are necessary, along with his comments andobservations about the waveform. The end results, including allannotations, are transferred in report and results files in step 1219 toan automatic importer. In an illustrative embodiment, a plurality ofviewing stations 1206 may receive time series data, such as ECG data,with the data distributed by the data control and queue manager 1202using call-center routing. In such an embodiment, incoming calls (e.g.,ECG data) may be directed to the next available user. However, callsneed not be processed in the order in which they are received at thecenter. For example, emergency calls may be given the highest priority,with other calls being assigned descending priorities depending on theirprocessing requirements.

[0074] As an illustrative example, the process whereby an ECG or othertime series data may be reviewed by a sequence of 2 users at twointeractive viewing stations in accordance with the principles of thepresent invention is shown in FIG. 12. The processing sequence may becontrolled by 1202 Data Control and Queue Management based on the usercapabilities, ECG specific processing requirements, or generalprocessing requirements, for example. As an illustrative example,additional user review steps may be added to the sequence if indicatedby processing requirements.

[0075] The block flow diagram of FIG. 13 illustrates in greater detailthe process whereby a user may review, change and approve a processedECG file in accordance with the principles of the present invention.Data, report and results are stored in storage 1300 and made availableto a technician's workstation 1206 through the data control and queuemanager 1202. For the user's review, the queue manager 1202 sendscurrent and comparison ECGs, in the form of report and results files tointeractive display 1206 in step 1301. Analysis and measurementprograms, which reside in this illustrative embodiment on theinteractive display in accordance with the principles of the presentinvention, include a 12— lead analysis engine 1302 to provide fulldetailed measurement and analysis of the ECG waveform or to provide are-assessment of the waveform based on changes made by the operator, arhythm analysis engine 1304 to provide a test specific set ofmeasurements and assessments for single or multi-lead rhythm tests, anda special measurement engine 1306 to provide non-standard measurementsand assessments of 12 lead resting ECGs, rhythm strips or other timeseries data that may be collected and presented. In accordance with thisillustrative embodiment, a user can accept marked measurements, rejectmarked measurements (by moving one or more markers), reprocess aninterpretation if measurement changes are made, or select alternativeanalysis/measurement processing.

[0076] The Current and Comparison Data Storage (shown in 1308) includesECG job data, patient demographic data, customer specific processingrequirements, account information, such as a patient site and sponsordata, complete waveform display data, and the complete report text. Thereport file and associated measurement and database files retain theoriginal computer measurements and interpretation and the history of allcompleted reviews and processing, including the latest cardiologistrevisions. The results file and associated files and databases containmarker and measurement information entered or calculated by the systemto allow annotation points and measurements to be displayed by theinvention. This includes: complete measurement matrix values from theanalysis program, such as detailed measurement values for features ineach lead, for example; sample point locations and values for each ofthe following items for each of the 12 leads: such as P onset, Pamplitude, P duration, Q onset, Q amplitude, Q duration, R onset, Ramplitude, R duration, S onset, S amplitude, S duration, J point, Jlevel, J+80 ms level, T onset, T amplitude, and T duration, for example.Multiple sets of sample location points will be stored when specialmeasurements have been made. Each time a change is made to the contentsof the results file, all old results are retained and the new resultsare appended with the appropriate identifiers, including reviewingoperator, date, and time. In an illustrative embodiment, each time asession is completed, the system requires the entry of a password toverify the identity of the operator.

[0077] As illustrated in FIGS. 10 and 11, the current invention supportsthe entry of codes, text and comments related to the interpretation ofthe time series data being presented and marked for measurement. In thecurrent invention, these entries may be checked for validity againsteach other and against the measurements determined by the markers aspart of a Quality Assurance process. The validity checking may result innot allowing certain combinations of contradictory entries or it mayallow entries to remain with confirmation that unusual values orcombinations of entries are correct. The Code Validation tab 1018 isused to display the results of this analysis for correction orconfirmation.

[0078] A user may select among various views and magnifications of ECGdata, as illustrated by the screen shots of FIGS. 3, 4, 7, 8, 9A, and9B. FIGS. 3 illustrates a 12 lead, standard height standard width, with12 leads at a time. FIG. 4 illustrates a 12 lead ECG in an alternateformat showing 2-6 lead by 5 second lead groups as previously described.These displays may be used, for example, to determine an overallevaluation of the data. FIG. 7 illustrates a double-height double-widthdisplay of the same ECG displayed in FIG. 4.This display may be used tomake detailed measurements. FIGS. 8, 9A, and 9B illustrate increasingmagnification of the waveform data to provide increased marker placementprecision. FIGS. 9A and 9B illustrate the option to display only asingle lead of data. FIG. 9B illustrates the use of the ½ scale displayoption that may be used for large amplitude waveforms.

[0079]FIG. 14 illustrates an additional method of displaying derived orcalculated data in conjunction with the original time series data. Inthis figure, the first time derivative of the time series data 1402 ispresented just below the original data 1401. Activation of this displayoption may be with the selection of a check box 1400, for example. Thepresentation of this data may be used to assist in the analysis of theoriginal data by helping to determine where the maximum rate of changeof the data occurs, for example. This same figure also illustrates howthe time series data for a comparison waveform may be presented in closealignment with the original data for comparison as an alternative to theside by side comparison display illustrated in FIG. 6, for example.

[0080]FIG. 15 illustrates an additional method of the current inventionfor displaying the original time series data by plotting 2 or more setsof the time series data against each other rather than against time. Asan illustrative example, the ECG lead values of lead I and lead aVF areplotted against each other 1500 to represent the frontal plane QRS axisloop. The plot results may be indicated with a label 1501 and activatedby a selection from a drop down menu, for example. The resultant twodimensional vector plot of heart activity within the body assists acardiologist in the analysis of a given ECG. FIG. 16 is an illustrativeexample of an exit screen that may be presented to a user when they havecompleted a review session. The process options 1600 allow the user toselect the next step or allow processing to continue as required. Theconfirmation password 1602 requires the confirmation by the user ofcompletion by entering their password.

[0081] As illustrated in FIG. 17, in response to user input or as aresult of computer analysis, ancillary lines may be drawn on the displaywith specific relationships to the time series waveform to assist in theanalysis of and marker placement on the time series data. Theseancillary lines may take the form of placing an isoelectric line 1700with relation to the time series data or the placement of a tangent line1701 at a particular point on the data, for example.

[0082] In an illustrative embodiment a user initiates the operation ofan interactive time-series data display in accordance with theprinciples of the present invention by a login process which may includesecurity processes that permit different levels of access to differentusers. After logging in, the system provides access to time-series datafor measurement. The time-series data, such as ECG data, may be storedand accessed though a database manager, for example, or the data may beprovided to the interactive display “real time” by connection to an ECGmachine. In a central processing embodiment, data is transmitted fromone or more ECG machines to a central location for processing by one ormore interactive display systems in accordance with the principles ofthe present invention.

[0083] An interactive display system in accordance with the principlesof the present invention provides an on-screen measurement function thatallows an operator, such as a cardiologist, to select one or moredisplayed points for the measurement of time-series data. The systemcaptures, not only the coordinates of the selected points, butcorresponding waveform coordinates, with a translation of thecoordinates into “real world” values, in microvolts and milliseconds,for example. The system also logs a record of all selections and editsand identifies the parties responsible for the selections. In anillustrative embodiment, the interactive display system provides areport file and a measurement matrix file related to such measurements.The report file, measurement file, and associated transaction orienteddata files may be individual files or may be configured as a set ofdatabase tables to contain all the required data related to the analysisand assessment of the original time series data.

[0084] An interactive display system in accordance with the principlesof the present invention may be used in the measurement, annotation, andanalysis of time-series data, such as ECG data. Various display formatsmay be employed, including those that emulate traditional strip-charthard-copy reports. The use of such traditional formats builds upon theexisting knowledge-base of those in the field, such as technicians andcardiologists, who have extensive training in the measurement, modeling,and analysis of such time-series records. The system may display datarelated to one or more channels, including time-series data from astandard twelve-lead ECG machine. Additional display formats, such asfrequency domain representations and other derived or processed data,may also be employed and displayed.

[0085] In an ECG measurement embodiment, the interactive display mayprovide a variety of display modes, including twelve-lead resting,60-second rhythm, 120-second, and longer rhythm displays. In atwelve-lead resting ECG, the leads may be plotted in a variety ofdisplay arrangements to optimize the information content of the displayfor the operator. Such arrangements may include display ofsimultaneously acquired data so that the time relationship of thedifferent waveforms is maintained for analysis, as well as the abilityto display data that is not simultaneously acquired either in its timesequence acquired format or in a more compact and understandable printedreport format. Examples of these types of display have been previouslymentioned as examples of printed report formats that the currentinvention emulates to take advantage of trained operator knowledge andexperience.

[0086] In addition to waveform representations, the display may alsoprovide for the display of additional information, such as acardiologist's comments and reports, for example. Such information maybe displayed in one or more separate “windows” located on the display,which windows may be opened or closed, re-sized, and re-positioned inresponse to user input. The interactive display may support measurementsin a variety of dimensions, including those represented by horizontaland vertical display axes.

[0087] Time series data that is displayed by an interactive display inaccordance with the principles of the present invention may be obtainedfrom a variety of sources, including stored digitized ECG data, datarepresenting scanned, digitized ECG paper records, or data received,directly or indirectly, and in some sense “live,” from an ECG device.The system is capable of capturing multiple records from differentsubjects, along with relationships among the recordings. Time-seriesdata such as may be displayed and measured through the use of aninteractive display in accordance with the principles of the presentinvention may be organized generally so that recordings from a patientin a single sitting is referred to as a session, and recordings over aperiod where experimental conditions are static will be referred toherein as a session.

[0088] Continuous, evenly-sampled data from a set of channels may bereferred to as an epoch. For example, in a twelve-lead ECG data obtainedfrom six leads, followed by data from six other leads, the data isorganized as two epochs of a single session. Data from a session may beorganized in a packet that includes a header identifying the person fromwho the recording was obtained, what equipment was used, and when therecordings began. Each epoch may identify data collectioncharacteristics, the characteristics of the channels, and annotationsthat apply across all channels. An epoch's data collectioncharacteristics include when the data collection started relative to thesession's baseline data and time and the sample rate for data on eachchannel, for example. Channel characteristics may include the number ofbits, zero-offset, units and scale factor by which data is to bemultiplied for conversion to given units. Filtering information, such ascharacteristics of bandpass, highpass, and lowpass, for example, mayalso be included.

[0089] Annotations at the session level can be used to indicate suchevents as when study procedures were performed relative to the recordingsession. Annotations at the epoch level may be used to mark featuresvisible in the data for multiple channels, e.g., PVCs or periods of A-Vblock. Annotations at the channel level would typically be used to markevents specific to that channel's data, for example, the beginning ofthe P wave. Each annotation may characterize a particular time point,denote the beginning and end of an interval, or may be associated withwhere a particular amplitude measurement is made. An interactive displayin accordance with the principles of the present invention may supportany of the following ECG-related measurements: duration of all or aselected part of a phase of the cardiac cycle, the amplitude ofparticular features in a cardiac cycle (absolute value or with respectto a reference iso-electric line or point), and the duration or presenceof periods of particular interest where notable events are taking place.Special measurements may include a requirement to determine a minimum orcertain number of annotation points in a certain specified lead or leadsso that particular protocol requirements can be met. The currentinvention may be able to provide a display of these requirements tofacilitate the efficient processing of these requirements.

[0090] The new interactive display may produce a report that includes: adigitized twelve-lead ECG waveform, patient demographics, and themeasurements and findings that are related to the analysis of the test.Additionally, the interactive display may, in response to a user promptor as a default, produce and display reduced data. For example, thedisplay may determine and display the average heart rate during a test,the longest PR interval associated with any lead, the longest QRSduration from any lead, or the longest QT interval from any lead.Additionally, the display system may produce and/or display the ratecorrected QT interval based on the QT and the average heart rate—using aselectable conversion methodology, or the frontal plane QRS axisdetermined from combinations of the limb leads. The interactive displaysystem supports study-specific special measurements, such asdetermination of the location of the maximum slope of a particularwaveform feature by calculating the time derivative of the originalsignal.

[0091] As described in relation to FIGS. 10 and 11, for example, thesystem may also provide for the display of interpretation codes andstatements. Such codes and statements may be automatically generated,using expert system, neural network, or other analysis systems, and maybe displayed in one or more “windows” within the display. Such windowsmay be fixed in position, size and other attributes or an operator mayresize, relocate, or otherwise alter the window for viewing orcomparison purposes. The interpretation codes and/or statements mayindicate a note worthy or abnormal ECG feature or finding, and mayinclude an overall assessment code, for example. The system may alsoprovide for the display of additional interpretive comments that may beentered, for example, by a reviewing cardiologist. Additionally, anoverall assessment code, a comparison statement, test identification,summary measurements and interpretations may be displayed in a separatetext area. Reports of abnormalities may be the result of computerinterpretation, with cardiologist review. The system may also check theentered interpretation codes and comments for consistency with themeasurements generated by the annotated data and with each other. Thisvalidity checking is provided as guidance to the operator concerningagreed to standards. The system may also provide additional checking toverify that all required special measurements have been completed priorto closing a session.

[0092] In an illustrative embodiment, a report file explicitly capturesthe data structure of a recording session, epochs comprising dataacquired over the same interval, and representations of data obtainedduring an epoch. The system may include a mechanism to annotate pointsin the time and intervals corresponding to single channels,representations, and sessions. Each report file may include a singleunique identifier created for each recording, which provides for anunambiguous link between each recording and other data stored for aparticular test in a study.

[0093] Pre-set marker information may be extracted from the report fileor the measurement matrix file and used to assist the technician in theinitial placement of the markers. Results of each markup session arestored in the database. Each time an ECG is reviewed, the most recentset of marker data will be used to pre-set the markers. The data from acardiologist's measurements and interpretation will be stored as part ofthe final report concerning the set of data being processed.

[0094] The system will use the locations of specifically annotated datapoints to derive or calculate values to be included in the report. Basedon standard electrocardiographic practice or special instructions for aparticular test, the operator will annotate the required points. Allsuch points that contribute to the analysis and interpretation of theECG may be included. The location of the annotated points are withreference to the beginning of the data for that lead and must includethe lead identification for the lead being measured in addition to theidentification label for the point. The invention will support theinclusion of annotation points in addition to those often used instandard analysis of ECGs. In an illustrative embodiment, the intervalsare derived from the indicated data points and will not require aseparate entry. PR, QRS, QT. All intervals may not be available for allleads. Data will only be recorded for those leads in which the intervalswere marked.

[0095] In accordance with the principles of the present invention, thesystem is able to annotate the presence of particular events ofinterest, including: Premature beats (by type) to include PVC's, PAC's,Ventricular Tachycardia, for example. An interactive display system inaccordance with the principles of the present invention provides aresolution of at least the sample period of the source data to determinethe location of the points and intervals. Higher resolution may also beprovided to allow estimates or calculations of annotation points to bemade between actual sample values. Measurements may be made across morethan one lead for ECGs that contain synchronous (simultaneouslyacquired) data. These measurements are classified as global in natureand may be used to help identify longest and shortest intervals for aset of leads.

[0096] Calculations may be made by the system for the intervals as theinterval end points are indicated. The measurements will be updated eachtime one of the markers involved in a measurement is moved. Measurementsfor the selected beat and for the average of the beats in the selectedlead will be updated as markers are placed or moved. Calculations may bemade for the following intervals. Leads without indicated points willnot be included in the calculation of the intervals. PR interval—P onsetto QRS onset, QRS duration—Q (QRS) onset to J point (QRS end), QT—Qonset to T end, Heart Rate—based on the average of consecutive R peaksthat are selected in a lead, and QTc—this value will use the QT intervaland the average R to R interval to determine the QTc value. Options forthe generation of the QTc value will be the use of the Bazeft formula(square root correction), Fredericia formula (cube root correction), theformula using the 2.5 root correction or linear correction, or otherformulae that may be required for rate correction of the QT interval.The minimum and maximum heart rate will also be recorded to allow thedisplay of the rate range information.

[0097] In the present invention a variety of statistical methods may beused to combine the individually determined measurements to determine arepresentative value for the measurement as the summary value for thetest. In an illustrative embodiment, if more than one interval isdetermined in a particular lead, then the average of the values in alead will be used as the value for that lead. If more than one leadcontains values for a particular measurement, then the maximum value forall the leads may be used.

[0098] Special measurements may be processed manually or withcomputational support. In an illustrative embodiment, support for thesemeasurements is made available by making the database tables to whichthese values must be entered available to the on-screen measurementsprogram to read. Additionally, the system allows an operator to readfrom study-specific special measurements table, the labelingrequirements, the database, table, field, and format. In an illustrativeembodiment, undesignated labels are available to allow making specialmeasurements and annotations. The labels and the associated database,table, field, and format information with the instructions for makingthe measurements may be automatically or manually loaded based oninformation provided with the test. These labels will be used toidentify the measurement or event marks in the same way as the standarddata points and intervals are identified. The instructions for aparticular measurement will be available under the general help functionor will be displayed when that special measurement mark is selected andthe Help button is pressed. This allows operators who are familiar withthe measurement to not have screen space taken up with the instructions.

[0099] As previously described, the system supports viewing comparisonECGs. An operator may select a comparison ECG (when one or morecomparisons are available) and view the associated report text andwaveforms. The user may not make any changes to the comparison ECG. TheECG report text will not be updated with the results of the processing.The details of what was changed, when it was changed, and who made thechanges will be recorded in a database as part of the tracking ofprocessing of the test. In an illustrative embodiment, the sessionrecords and results file records are an integral part of the databaseand are available to be exported.

[0100] Output to database tables may include the output from themeasurement markup portion of the interactive display engine, includingall measurement points with the label for each point or interval, thelead in which the measurement was made, the location of the point, inmilliseconds, from the beginning of the lead, and the end point, inmilliseconds, for an interval. For global measurement points orintervals, the lead designation will designate the lead group with whichthe markers are related. Also included in the database is the login IDof the person making the changes. Current changes will not obscure therecord of previous changes made to the file. All changes, includingchanges back to original values will be retained. The options andsettings that were used during the changes, including the maximummagnification used, the waveform plot and marker line widths (finalsettings), and the marker color set will be recorded. The followingitems will also be recorded: the date and time when the session wasbegun and when it ended, the lead length of each lead and the offsetfrom the earliest lead, (a zero entry would indicate that no offset ispresent and the lead so indicated is synchronous with the other leadwith an offset of 0), whether a filter was used, and the type of filter,if the data was filtered. This information may be supplied in differentways depending on the procedures used to process the test.

[0101] A software implementation of the above described embodiment(s)may comprise a series of computer instructions either fixed on atangible medium, such as a computer readable media, e.g. diskette,CD-ROM, ROM, or fixed disc, or transmittable to a computer system, via amodem or other interface device, such as communications adapterconnected to the network over a medium. Medium can be either a tangiblemedium, including but not limited to, digital or analog communicationslines, or may be implemented with wireless techniques, including but notlimited to microwave, infrared or other transmission techniques. Theseries of computer instructions embodies all or part of thefunctionality previously described herein with respect to the invention.Those skilled in the art will appreciate that such computer instructionscan be written in a number of programming languages for use with manycomputer architectures or operating systems. Further, such instructionsmay be stored using any memory technology, present or future, including,but not limited to, semiconductor, magnetic, optical or other memorydevices, or transmitted using any communications technology, present orfuture, including but not limited to optical, infrared, microwave, orother transmission technologies. It is contemplated that such a computerprogram product may be distributed as a removable media withaccompanying printed or electronic documentation, e.g., shrink wrappedsoftware, preloaded with a computer system, e.g., on system ROM or fixeddisc, or distributed from a server or electronic bulletin board over anetwork, e.g., the Internet or World Wide Web.

[0102] Although various exemplary embodiments of the invention have beendisclosed, it will be apparent to those skilled in the art that variouschanges and modifications can be made which will achieve some of theadvantages of the invention without departing from the spirit and scopeof the invention. It will be apparent to those reasonably skilled in theart that other components performing the same functions may be suitablysubstituted. Further, the methods of the invention may be achieved ineither all software implementations, using the appropriate object orprocessor instructions, or in hybrid implementations that utilize acombination of hardware logic, software logic and/or firmware to achievethe same results. Processes illustrated through the use of flow chartsmay not be strictly linear processes and alternative flows may beimplemented within the scope of the invention. The specificconfiguration of logic and/or instructions utilized to achieve aparticular function, as well as other modifications to the inventiveconcept are intended to be covered by the appended claims.

[0103] The foregoing description of specific embodiments of theinvention has been presented for the purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and many modifications andvariations are possible in light of the above teachings. The embodimentswere chosen and described to best explain the principles of theinvention and its practical application, and to thereby enable othersskilled in the art to best utilize the invention. It is intended thatthe scope of the invention be limited only by the claims appendedhereto.

What is claimed is:
 1. A method of marking time-series medical data thatis graphically displayed in the form of a trace, comprising the stepsof: a controller accepting user input to locate a displayed medicaltrace feature; the controller placing a first mark related to adisplayed medical trace feature; the controller labeling the placed markby displaying a label identifying the placed mark; and the controllerautomatically labeling subsequent medical traces with correspondinglabels as those features are located.
 2. The method of claim 1 whereinthe step of the controller accepting user input includes the step of:the controller accepting user input that indicates a type ofelectrocardiogram (ECG) sequence for which a feature is to be located.3. The method of claim 2 wherein the controller further applies a labelby displaying a reference line between the mark and the label.
 4. Themethod of claim 2 wherein the step of the controller accepting userinput includes the step of: the controller accepting input from a user,the input indicating that a PQJT sequence is to be labeled.
 5. Themethod of claim 4 wherein the step of the controller accepting userinput includes the step of: the controller accepting user input from agraphical user interface.
 6. The method of claim 5 wherein thecontroller applies a label to the first mark located in response to userinput by displaying a “P” in proximity to the mark.
 7. The method ofclaim 2 wherein the step of the controller accepting user input includesthe step of: the controller accepting input from a user, the inputindicating that a QPJT sequence is to be labeled.
 8. The method of claim7 wherein the controller applies a label to the first mark located inresponse to user input by displaying a “Q” in proximity to the mark. 9.The method of claim 2 wherein the step of the controller accepting userinput includes the step of: the controller accepting input from a user,the input indicating that a QRS onset is to be labeled.
 10. The methodof claim 9 wherein the controller applies a label to the first marklocated in response to user input by displaying a Q onset label inproximity to the mark.
 11. The method of claim 10 wherein the controllerapplies a label to the second mark located by displaying a P onset labelin proximity to the mark.
 12. The method of claim 2 further comprisingthe step of displaying time series medical as a trace superimposed on agridded background.
 13. A method of marking time-series medical datacomprising the steps of: a controller accepting user input to locate adisplayed medical trace feature; the controller placing a first markrelated to a displayed medical trace feature; the controller labelingthe placed mark by displaying a label identifying the placed mark; thecontroller automatically labeling subsequent medical traces withcorresponding labels as those features are located; the controllerfurther accepting user input that indicates a type of electrocardiogram(ECG) sequence for which a feature is to be located; and the controllerdisplaying time series medical as a trace superimposed on a griddedbackground of rectangular cells that delimit 40 millisecond by 0.1millivolt sections of grid-space.
 14. The method of claim 13 furthercomprising the step of the controller displaying a gridded background ofsuper-cells that each delimit 200 milliseconds by 0.5 millivolts ofgrid-space.
 15. An apparatus for marking time-series medical comprising:a controller configured to accept user input to locate a displayedmedical trace feature; the controller configured to place a first markrelated to a displayed medical trace feature; the controller configuredto label the placed mark by displaying a label identifying the placedmark; and the controller configured to automatically label subsequentmedical traces with corresponding labels as those features are located.16. The apparatus of claim 15 wherein the controller is furtherconfigured to accept user input that indicates a type ofelectrocardiogram (ECG) sequence for which a feature is to be located.17. The apparatus of claim 16 wherein the controller is furtherconfigured to accept input from a user, the input indicating that a PQJTsequence is to be labeled.
 18. The apparatus of claim 17 wherein thecontroller is further configured to accept user input from a graphicaluser interface.
 19. The apparatus of claim 16 wherein the controller isfurther configured to accept input from a user, the input indicatingthat a QPJT sequence is to be labeled.
 20. The apparatus of claim 16wherein the controller is further configured to accept user input thatindicates that a QRS onset is to be labeled.
 21. The apparatus of claim16 wherein the controller is configured to display time series medicaldata as a trace superimposed on a gridded background.
 22. An apparatusfor marking time-series medical data comprising: a controller configuredto accept user input to locate a displayed medical trace feature; toplace a first mark related to a displayed medical trace feature; tolabel the placed mark by displaying a label identifying the placed mark;to automatically label subsequent medical traces with correspondinglabels as those features are located; the controller further configuredto accept user input that indicates a type of electrocardiogram (ECG)sequence for which a feature is to be located; and the controllerconfigured to display time series medical data as a trace superimposedon a gridded background of rectangular cells that delimit 40 millisecondby 0.1 millivolt sections of grid-space.
 23. The apparatus of claim 22wherein the controller is further configured to display a griddedbackground of super-cells that each delimit 200 milliseconds by 0.5millivolts of grid-space.